1. Field of the Invention
The invention relates to an inkjet image-forming apparatus and a printing method, and specifically, to an image-forming apparatus and a printing method which are capable of reducing both the mist production and the influence caused by the produced mist as well as capable of reducing time to start a printing operation under a low-temperature environment.
2. Description of the Related Art
Inkjet printers, which have been widely used, form images by ejecting ink onto a printing sheet from printing heads. Printing heads in inkjet printers eject ink by applying a driving voltage to an ink-ejection mechanism such as a piezoelectric element. The ink used in inkjet printers typically has characteristics that the ink increases its viscosity under a low-temperature environment. Therefore, the amount of ink to be ejected is not enough under the application of the driving voltage that is applied in ordinary occasions (hereafter, simply referred to as the “ordinary driving voltage”). Accordingly, under a low-temperature environment, heaters are used to warm the ink and printing is started only after the ink is warmed up to an appropriate temperature. For this reason, a problem arises that a print-start time delays when the inkjet printer is used under a low-temperature environment. The problem becomes more noticeable in the case of ink-circulation type inkjet printers each equipped with an ink-circulation route, because the ink-circulation type inkjet printer has a larger amount of ink to be heated.
The inkjet printer disclosed in Japanese Patent Application Publication No. 2007-296754 has not only a problem that the print-start time delays due to the increased viscosity of ink under a low-temperature environment, but also a problem that mist, which is unnecessary microscopic ink droplets produced when the ink is ejected, attaches to the printing sheet or the inside of the printer chassis, resulting in a lower-quality print.